Control mechanism for etching machine



Oct. 8, 1963 T. HENDERSON CONTROL MECHANISM FOR ETCHING MACHINE Filed May 26, 1961 4 Sheets-Sheet 1 INVENTOR. THOMAS HENDERSON BY /%p/"/M, myam, 211%: f

ATTO RN EYS 06L 1963 T. HENDERSON CONTROL MECHANISM FOR ETCI-{ING MACHINE Filed May 26, 1961 4 Sheets-Sheet 2 INVENTOR. THOMAS HENDERSON BY v fl/wym Fimym, flml m 7411 AT To R N E YS Oct. 8, 1.963 T. HENDERSON 3,106,217

CONTROL MECHANISM FOR ETCHING MACHINE Filed May 26, 1961 4 Sheets-Sheet 3 FIG.6.

49 AGITATOR g TR 50 r w K f/ TIMER MTR I' l G- '7.

AGITATOR MTR INVENTOR.

THOMAS HENDERSON ATTORNEYS Oct. 8, 1963 'r. HENDERSON 3,106,217

CONTROL MECHANISM FOR ETCHING MACHINE Filed May 26, 1961 4 Sheets-Sheet 4 F' IG. 8-

F G. IO. VARIABLE MTR - LOW SPEED DRIVE CLUTCH /34 c 0 HIGH SPEED DRIvE CLUTCH 46 TIMER 44 MTR F l G. 9.

VARIABLE MTR INVENTOR. THOMAS HENDERSON BY MM, Fmgm, 2mm 2 WW ATTORNEYS United States Patent 3,106,217 CONTRUL MEQHANESM FOR ETCHING MACHENE Thomas Henderson, Locust Valley, N.Y., assignor to Powers Chemco, Inc, Glen Cove, N.Y., a body corporate of New York Filed May 26, 1961, Ser. No. 113,594 Claims. (Cl. 134-58) etched plate removed from the housing until the next printing plate is ready to be etched.

The acid etching solutions for etching of printing plates are generally composed of several ingredients. For example, etching copper plates, the solution may include ferric chloride and thiourea; for etching zinc or magnesium plates, the solution may include nitric acid, diethyl benzene, a sodium salt of diethyl sulfosuccinic acid and polyvinyl pyrrolidone. To operate properly, the etching solutions must be maintained in an emulsified condition with a homogeneous solution in uniform contact with the plate. It is, therefore, necessary to insure that no separation of solution ingredients occurs between successive etching operations despite the elapsed time therebetween.

Several attempts have been made to overcome the problem of separation. One attempt included mounting a system of spray pipes in the tank to maintain the solution in agitated condition between etching operations. Another attempt included the use of a separate system of paddles for agitating the solution between etching operations. However, these devices were inefiicient and increased substantially the cost of the etching machine.

The present invention is characterized by the provision of a novel operating and control system for the splash paddles whereby the paddles are selectively rotated at the proper etching speed during the etching operation and, between successive etching operations, are effective to maintain the etching solution in thoroughly mixed condition. The system includes a low speed drive for the agitator paddles operative at the end of the etching operation to continuously agitate the etching solution. The system also comprises a high speed drive for rotating the paddles during the etching operation and interlocked operating means for selectively cpntrolling the timed operation of the paddle drives.

In the preferred embodiments of the invention, two separate motors are utilized and interconnected'by clutch means and an electrical operating circuit for energizing the low speed motor whenever the high speed motor is deactivated; as at the end of the etching cycle.

In other embodiments of the invention, a single adjustable speed motor is employed which is operatively associated with a pair of clutches for the high and low speed paddle drives, and an electrical operating circuit is employed for selectively coupling one of the clutches to the motor.

Objects It is the object of the present invention to provide, in an etching machine, an improved mechanism for maintaining the etching solution in thoroughly mixed condition between successive etching operations.

It is a further object of the invention to provide, in an etching machine utilizing rotatable splash paddles, a novel operating and control system for selectively rotating the paddles at etching speed during the etching operations and at a slower speed between etching operations to maintain the etching solution in emulsified condition.

Another object of the invention is to provide, for the rotatable splash paddles of an etching machine, a solution agitating drive for the paddles and an etching splash drive for the paddles and an interconnected operating system for selectively controlling the timed operation of the drives.

An added object of this invention to provide in an etching machine an improved mechanism for agitating the etching solution therein which is simple, efiicient and inexpensive.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions,

arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

In the drawings, wherein like numerals designate like parts:

FIG. 1 is a perspective view of the preferred embodiment of the present invention.

FIG. 2 is a perspective view of a modified form of the present invention.

FIG. 3 is a perspective view of still another modified form of the present invention.

FIG. 4 is a perspective view of another modification of the present invention.

FIG. 5 is a perspective view of still another modification of the present invention.

FIGS. 6-10 are schematic wiring diagrams for a suitable electrical control circuit associated with each embodiment of the present invention.

Turning specifically to FIG. 1, there is illustrated the preferred embodiment of the invention which includes a tank or housing 10, shown schematically, which is adapted to hold a suitable etching fluid. Tank 10 is provided with a lid or cover (not shown) which encloses tank 10 and provides access to the inside thereof. The cover (not shown) includes on its underface, mechanism for supporting a printing plate within housing 10. Tank 10 and the cover (not shown) and their associated mechanism may be similar in construction and operation to that disclosed in Easley et al. Patent No. 2,669,048 or in Guenst Patent No. 2,700,838, or in Anander Patent 2,762,151.

During the etching operation, with the cover (not shown) in closed position and a printing plate disposed within tank 10, means is provided for continuously splashing or spraying the etching fluid [against the face of the printing plate supported by the cover. This means includes a plurality of spaced transverse shafts 12 rotatably supported at each end in suitable bearings carried by channel brackets 14 and 15 of the main machine frame. Each shaft 12 carries a paddle 16 clamped to and extending the length of the shaft, the width of the paddle 16 being sufficient to dip the outer extremities thereof into the etching solution when tank 10 is properly filled with etching solution.

{The end of each shaft 12 adjacent bracket 14 is provided with a sheave or pulley 18 for rotating its asso- 3 ciated shaft '12. and paddle 16. A single endless belt 2t) is trained over each of the pulleys 18 to rotate pulleys 18 in common. Idler pulley 21 rotatably supported adjustably in a bracket (not shown) carried by the main machine frame is provided to maintain proper tension on belt 20.

Belt 2t) is also trained about a sheave or pulley 2'2 fixed to the free end of a drive shaft 24. Shaft 24 includes a second pulley or sheave 26 spaced from sheave 22. and about which is trained one end of an endless belt 28. T he other end of belt 28 is trained around pulley 3t} fixed to the output shaft 32 of a suitable constant, low-speed, agitator motor 34. 'In addition, shaft 24 is coupled by means of an overrunning one-way sprague clutch member 36 to the output shaft 3-8 of a suitable, variable-speed,

splash motor 40.

-In operation, etching solution is placed on the tank 10 to the required level, and agitator motor start-stop switch &2 is depressed by the operator. As shown in FIG. 6, this completes a circuit energizing motor 34 which, through belts 2t and 28 and pulleys d8, 22, 26 and 30, rotates paddles 16 in tank 20. Preferably, paddles 16 are rotated at approximately 100 r.p.m. by motor 34 to effect complete dispersion and emulsification of the etching solution ingredients in tank 10.

When a plate is ready to be etched, it is mounted on the inner face of the cover (not shown) and for positioning within tank 10, as disclosed in the aforementioned Easley and Guenst patents. As the cover is travelled into closed position, disposing the printing plate to be etched inside tank 10, the cover engages and closes normally-open switch 44. The closing of switch 44 by the cover completes an electrical circuit energizing a suitable synchronous timer motor d6. Motor 46 is constructed and arranged to remain energized until its timing cycle is completed, at which time it is automatically de-actuated. A suitable timer motor for this purpose is the Eagle Cycl- Flex motor, commercially available from the Eagle Signal Corp., Moline, Ill.

In addition, the circuit completed by closing switch 44 energizes double contact relay 47, moving contacts 48 thereof out of engagement with contacts 49 in t e circuit energizing motor 34. In turn, contacts 50' of actuated relay 46 are moved into engagement with cooperating contacts 51, completing a circuit energizing splash motor 44). Thus, closing of the cover simultaneously effects deactuation of agitator motor 34, actuation of splash motor 40 and timer motor 45, starting the timed etching cycle.

At the end of the etching operation, as determined by timer motor 46, the timer motor circuit is interrupted, deact'uating relay 46. Deactu-ation of relay 46 thus stops splash motor 40 and restarts agitator motor 34. Motor 34 remains actuated to maintain the etching solution in emulsified condition, awaiting the next printing plate to be etched.

FIG. 2 discloses a modification of the present invention wherein the operating mechanism for paddle belt drive pulley 22 includes an operating shaft 52 on one end of which pulley 2:2 is mounted. The other end of shaft 52 supports a second sheave or pulley 54 around which is trained an endles belt '56. Belt 56 is trained, at its other end, around a pulley *8 fixed to a shaft 60 which is coupled by a suitable electromagnetic clutch 62 to the output shaft 63 of agitator motor 34.

Intermediate pulleys 22 and 54, shaft 52 also supports a third sheave 64. An endless belt 66 is trained at one end about sheave 64'. At its other end, belt 65 passes around sheave 68 which is fixed to a shaft 70 coupled by a suitable electromagnetic clutch 72 to the output shaft 74 of splash motor. 40.

In operation, after the proper amount of etching solution has been added to tank '10, switch '42 of FIG. 7 is depressed by the operator. As shown in FIG. 7, this completes the circuit actuating motor 34, simultaneously energizing normally-disengaged clutch 62 to couple shafts 63 and 63 in driving engagement. Coupling of shafts 60 and '63 in driving engagement effects rotation of paddles 16 through the action of belts 2i) and '56 and pulleys d8, 22, 54 and 58. Preferably, paddles '16 are rotated at r.p.m. to maintain the etching solution in mixed condition.

As the cover, supporting a plate ready to be etched, is travelled into closed position, it engages and closes normally-open switch 44. Closing of switch 44 completes a circuit energizing synchronous timer motor 46 which remains energized until its timing cycle has been cornpleted. In addition, the circuit completed by the closing of switch 44 energizes double contact relay 47, interrupting the circuit energizing clutch 62 and motor 34 and completing the circuit actuating normally-disengaged clutch '72 and motor A). Energizing of clutch 72 effects coupling of shafts 7d and 74 in driving engagement, thereby rotating paddles 16 through the action of belts 2i? and 66 and pulleys 18, 22, 64 and 63. Preferably, paddles 16 are rotated between 500 and 700 r.p.m. during the etching operation.

At the end of the etching operation as determined by timer motor as, the circuit actuating clutch 72 and motor 40 is interrupted while the circuit actuating clutch 62 and motor 34 is re-established by relay 46. Paddles 16 are thus re-associated with agitator motor 84 to maintain the etching solution in mixed condition for the next printing plate to be etched.

FIG. 3 discloses another modification of the present invention wherein the operating mechanism for paddle belt drive pulley 22* includes an operating shaft 76 on one end of which pulley 22 is fixed. The other end of shaft 76 freely supports a second pulley 78 around which is trained an endless belt 80. Belt 8% also passes around a drive pulley 3A2 fixed to the output shaft 32 of motor 3-4.

Included on shaft 76 is a third freely-mounted pulley 84 positioned thereon between pulleys 22 and 78. One end of an endless belt 36 passes around pulley 84 while the other end of belt 86 is trained around a pulley 88 fixed to output shaft 38 of motor 44).

In addition, shaft 76 slidably supports a double throw mechanical clutch 9t loomed ion shaft 76 between pulleys S4 and 78. Clutch 9% is axially movable on shaft 76 but rotatable therewith. An operating \arm 92 fixed at one end to clutch 96 includes at its other end a transverse extension 94 which is provided with a resilient member, such as spring 96, normally biasing clutch 99 into driving engagement with pulley 78. Extension d4 also includes a normally-extended solenoid 98 for selectively urging clutch 39 into driving engagement with pulley 84 against the action of spring 96.

In operation, after the proper amount of etching solution has been added to tank It actuation of switch 42 of FIG. 8 starts agitator motor 3%. Since solenoid 98 is extended and spring 96 normally urges clutch 9% into driving engagement with pulley 7 8, rotation of shaft 32 of motor 34 and pulley 32 effects rotation of pulley 78 which, in turn, is transmitted to shaft 76. Thus actuation of motor 34 effects rotation of paddles 16 through the action of belts 2t) and Sdand pulleys i8, 22, 78 and 82, preferably at 100 revolutions per minute.

When switch 44 is closed by the cover being travelled into closed position, the circuit completed thereby simultaneously deactuates motor 34 while actuating timer motor 4-5 and splash motor 40. Also this circuit actuates solenoid 98 retracting its armature and sliding clutch 9% on shaft 76 into driving engagement with pulley 8-itransmitting rotation of pulley 84 to shaft 76. Thus actuation of motor 4% and solenoid 93 effects rotation of paddles 15 thus the action of belts 2t) and 86 and pulleys 18, 22, 84 and 88, preferably at 500700 revolutions per minute.

At the end of the etching operation, as determined by timer motor 46, the circuit actuating solenoid 3 and motor 4% is interrupted while the circuit actuating motor 34 is re-established, by relay 47. Spring 96-effects reengagement of clutch 90 and pulley 78. Thus paddles 16 are re-associated with agitator motor 34 to maintain the etching solution in mixed condition tor the next printing plate to be etched.

FIG. 4 discloses another modification of the present invention utilizing a single variable speed motor for rotating paddle 16 during the agitating and splashing operations described hereinabo-ve in connection with the preferred embodiment. In this modification, pulley 22 is mounted on one end of a shaft 1% which is provided with a second pulley 1112 at the other end thereof. Pulley 113 2 is fixed to and rotates with shaft 160 and has an endless belt 1614 trained therearound. The other end of belt 104 passes around a pulley 106 freely supported on the end of output shaft 1% of variable speed motor 40.

Shaft 101) also includes a third pulley 110 fixed to and rotatable therewith. One end of an endless belt 112 passes around pulley 110 and is trained at its other end around pulley 11 1 freely supported on shaft 111%. A double throw clutch mechanism 116 supported on shaft 168 between pulleys 106 and 114, is axially movable on shaft 163 but rotatable therewith. An operating arm 118 fixed at one end to clutch 116 includes, at its other end, a transverse extension .120. Extension 120, in turn, is secured to a resilient member, such as spring 122, which normally biases clutch 116 into driving engagement with pulley 1%. Extension 121} also includes a normally extended solenoid 124 fixed thereto for selectively urging clutch 116 into driving engagement with pulley 114- against the action of spring 122.

In operation, after the proper amount of etching solution has been added to tank 11 actuation of switch 42 of FIG. 9 completes a circuit energizing variable speed motor 46. However, since solenoid 124 is still de-activated, spring 122 effects driving engagement between shaft 103 and pulley 166. This in turn rotates paddles 16 through the action of belts 26 and 1114 and pulleys 13, 22, 1132 and 1&6, preferably at 100 r.p.m., to agitate the etching solution.

When the cover is closed at the start of the etching operation, the circuit completed by closing cover switch 44 actuates timer motor 46 and energizes solenoid 124. Solenoid 124 thus slides cl-uttch 116 into driving engagement with pulley 114, thereby disengaging pulley 106 from rotation with shaft 108. Engagement of clutch 116 and pulley 114 thus effects transmission of rotation to paddles 16 through the action of belts 2d and 112, and pulleys 18, 22, 111 and 114, preferably at 500-700 rpm. during the etching process.

Pulleys 106, 111) and 114 are preferably of the same effective diameter. Pulley 1192, however, is of a greater effective diameter than pulley 111 Thus the ratio between the speed of rotation of paddles 16 when driven by pulley 110, and the speed thereof when driven by pulley 1G2, is the ratio between the effective diameters of pulleys 110 and 1112. However, it will be understood that with pulleys 106 and 114 and their assooiated belts 10 4 and 112 driven at the same speed by motor 419, pulley 102, having the larger diameter, rotates at a slower speed than does pulley 111) when these pulleys are driven by their associated belts 1'14- and 112. Therefore, when pulley 102 effects rotation of paddles 16, they rotate at a slower speed than when pulley 110 is effecting rota-tion of paddles 16. Thus with a given speed of rotation of output shaft 168 of motor 40, the ratio between the agitating and etching or splash speeds of paddles 16 will be constant and a function of the diameter ratio of pulleys 1612 and 110.

At the end of the etching operation, as determined by timer motor 46, the circuit actuating solenoid 124 is interrupted, permitting spring 122 to re-engage clutch 116 and pulley 106. Paddles 16 are thus re-associated 6 with pulley 102 to maintain the etching solution in mixed condition for the next printing plate to be etched.

FIG. 5 discloses still another modified form of the present invention utilizing a single variable speed motor for paddles 16 and wherein the operating mechanism for pulley 22 includes a shaft 126 on which pulley 22 is axially secured adjacent the middle of shaft 126. One end of shaft 126 is provided with a pulley 128 fixed thereto. The endless belt 130 passes around pulley 123 and pulley 132 which is coupled by a suitable electromagnetic clutch 134 to the output shaft 136 of variable speed motor 138.

The other end of shaft 1-26 is also provided with a pulley 1 1i Endless belt 142 is trained around pulley and around a pulley 14 4 coupled by a suitable electromagnetic cl-utch 146 to a second output shaft 148 of motor 13%.

Preferably, motor 138 is constructed with a constant speed shaft 148 and an adjustable speed shaft 136. Shaft 136 is effective to rotate paddles 16 during the etching or splashing operation. Fixed speed shaft 148 is efiective to rotate paddles 16 during the agitating operation.

In operation, when the proper amount of etching solution has been added to tank 11), actuation of switch 42 of FIG. 10 energizes motor 138, thereby effecting rotation of shafts 136 and 148. Simultaneously, clutch 146, normally disengaged from pulley 144, is energized, coupling pulley 144 in driving engagement with shaft 148. Thus paddles 16 are rotated in tank 10 through the action of pulleys 18, 22, 146 and 140 and belts 20 and 142, preferably at 100 r.p.m., to maintain emulsification of the etching solution.

As the cover and a printing plate thereon close switch 44 at the start of the etching operation, the circuit completed thereby energizes timer motor 46 to start the etching cycle. Completion of this circuit also energizes double contact relay which interrupts the circuit energizing clutch 146, disengaging pulley 144 and shaft 148 while establishing a circuit energizing normallydisengaged clutch 134. Energizing of clutch 134 couples pulley 132 to shaft 136 to rotate paddles 16 through the action of pulleys 13, 22, 128 and 132, and belts 20 and 131i. Preferably, paddles 16 are driven by shaft 136 at 500-700 rpm. during the etching operation.

At the end of the etching operation as determined by timer motor 16, the circuit actuating relay 15 0 and clutch 134 is interrupted while the circuit actuating clutch 146 is re-established. Paddles 16 are thus re-associated with shaft 148 to maintain the etching solution in mixed con dition for the next printing plate to be etched.

Thus there is disclosed a simple, eflicient control mechanism for selectively rotating the etching paddles of an etching machine at a first speed to maintain agitation of etching solution ingredients and at a second speed to effect etching of printing plates.

The invention in its broader aspects is not limited to the specific mechanism shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

:What is claimed is:

1. In an etching machine having a plurality of rotatable paddles therein for spraying etching solution against a printing plate, the combination comprising a tank for containing said etching solution, means mounting said paddles for rotation in said tank, with a portion of the paddles disposed in said etching solution, means for rotating said paddle mounting means and said paddles at a first given speed to maintain the ingredients ofsaid etching solution in mixed condition, means for rotating said paddle mounting means and said paddles at a second given speed during the etching operation to splash said etching solution against a printing plate disposed within said tank and means including timer means for selectively Z interconnecting said paddle mounting means and rotating means for normally rotating said paddles at said first given speed, said timer means automatically interconnecting said paddle mounting means and rotating means for rotating said paddl s at said second given speed during the etching operation as determined by said timer means.

2. In an etching machine having a plurality of rotatable paddles therein for spraying etching solution against a printing plate, the combination comprising a tank for containing said etching solution, means mounting said paddles for rotation in said tank, with a portion of the paddles disposed in said etching solution, means for rotating said paddle mounting means and said paddles at a first given speed to maintain the ingredients of said etching solution in mixed condition, mews for rotating said paddle mounting means and said paddles at a second given speed during the etching operation to splash said etching solution against a printing plate disposed within said tank, and means selectively interconnecting said rotating means for normally rotating said paddles at said first given speed and for rotating said paddles at said second given speed during the etching operation, said first given speed being substantially slower than said second given speed and including at least one drive motor for rotating said paddles, a timer motor for timing said etching operation, an electrical operating circuit for said drive motor and said timer motor, switch means for energizing said drive motor, said operating circuit and said paddle rotating means adapting said paddles and paddle mounting means for normal rotation at said first given speed, means for energizing said timer motor at the start of the etching operation while concomitantly connecting said paddle mounting means and second-speed rotating means disconnecting said paddle mounting means and firstspeed rotating means, thereby automatically increasing the speed of rotation of said paddles from said first given speed to said second given speed, and means at the end of said etching operation as determined by said timer motor for disconnecting said paddle mounting means and said second-speed rotating means and re-connecting said paddle mounting means and said first-speed rotating means, thereby returning the speed of rotation of said paddles from said second given speed to said first given speed until the next successive etching operation.

3. In an etching machine having a plurality of rotatable paddles therein for spraying etching solution against a printing plate, the combination comprising a tank for containing said etching solution, means mounting said paddles for rotation in said tank with a portion of said paddles disposed in said etching solution, at least one drive motor for said paddles, means for efiecting rotation of said paddles from said drive motor at a first given speed to maintain the etching solution ingredients in mixed condition, means for effecting rotation of said paddles from said drive motor at a second given speed during the etching operation to splash said solution against a printing plate disposed within said tank, and clutch means for selectively connecting said motor with a particular one of said first rotating means and said second rotating means, a timer for timing saidetching operation, and means interconnecting said clutch means and said timer whereby said second rotating means is associated With said motor at the start of the etching operation and said first rotating means is associated with said motor at the end of the etching operation as determined by said timer until the next successive etching operation.

4. In an etching machine 'having a plurality of rotatable paddles therein for spraying etching solution against a printing plate, the combination comprising a tank for containing said etching solution, means mounting said paddles for rotation in said tank with a portion thereof disposed in said etching solution, means for rotating said paddles including a first drive motor for rotating said paddles at a first given speed, a second drive motor for rotating said paddles at a second given speed, clutch east? means for selectively associating a particular one of said first and said second motor with said paddles, a timer motor for timing said etching operation, an electrical operating circuit for said drive motors and said timer motor, switch means for energizing said first motor, means for connecting. said clutch means with said first motor to rotate said paddles at said first given speed to maintain the ingredients of said etching solution in mixed condition, means for energizing said second motor and said timer motor at the start of the etching operation while simultaneously connecting said clutch means with said second motor whereby said paddles are rotated at said second given speed during the etching operation, and means at the end of the etching operation as determined by said timer motor for re-connecting said paddles with said first motor.

5. The invention as defined in claim 4 wherein said clutch means includes a first electro-mechanical clutch in said circuit for said first motor, a second electromechanical clutch in said circuit for said second motor and means interconnecting said clutches in said circuit for actuation of the particular clutch upon actuation of its associated motor.

6. The invention as defined in claim 4 wherein said clutch means includes a double-acting clutch, spring means normally connecting said clutch with said first motor and an electro-responsive element in said operating circuit for connecting said clutch with said second motor upon actuation of said second motor.

7. The invention as defined in claim 4 including means normally connecting said paddle rotating means with said second motor and a coil clutch operative to transmit rotation in one direction only for effecting rotation of said paddle rotating means upon actuation of said first motor means.

8. In an etching machine having a plurality of rotatable paddles therein for spraying etching solution against a printing plate, the combination comprising a tank for containing said etching solution, means mounting said paddles for rotation in said tank with a portion of said paddles disposed in said etching solution, a drive mot-or for said paddles, means for effecting rotation of said paddles from said drive motor at a first given speed to maintain the etching solution ingredients in mixed condition, means for effecting rotation of said paddles from said drive motor at a second given speed, during the etching operation to splash said solution against a printing plate disposed within said tank, clutch means for selectively connecting said motor with said first rotating means, a timer motor for timing said etching operations, an electrical operating circuit for said drive motor and said timer motor, switch means for energizing said drive motor, means normally connecting said clutch with said first rotating means, means for energizing said timer motor at the start of said etching operation While simultaneously connecting said clutch means with said second rotating means, and means at the end of the etching operation as determined by said timer motor for re-connecting said clutch with said first rotating means.

9. The invention as defined in claim 8 wherein said clutch means includes a first electromechanical clutch in said circuit for said first rotating means, a second electromechanical clutch in said circuit for said second rotating means, and means interconnecting said clutches in said circuit for alternative operation whereby said first electromechanical clutch is normally actuated with said drive motor and second clutch is actuated only during the etching operation.

10. The invention as defined in claim 8 wherein said clutch means includes a double-acting clutch, spring means normally connecting said clutch with said first rotating means and an electro-responsive element in said operating circuit for connecting said clutch with said second rotating means during the etching operation.

(References on following page) 9 References Cited in the file of this patent UNITED STATES PATENTS 1,904,391 Solie et a1. Apr. 18, 1933 2,002,795 Przyborowski May 28, 1935 5 2,061,775 Panos let a1 Nov. 24, 1936 837, 87

Easley et a1 Feb. 16, 1954 Guenst Feb. 1, 1955 Anander Sept. 11, 1956 FOREIGN PATENTS Great Britain June 15, 1960 

1. IN AN ETCHING MACHINE HAVING A PLURALITY OF ROTATABLE PADDLES THEREIN FOR SPRAYING ETCHING SOLUTION AGAINST A PRINTING PLATE, THE COMBINATION COMPRISING A TANK FOR CONTAINING SAID ETCHING SOLUTION, MEANS MOUNTING SAID PADDLES FOR ROTATION IN SAID TANK, WITH A PORTION OF THE PADDLES DISPOSED IN SAID ETCHING SOLUTION, MEANS FOR ROTATING SAID PADDLE MOUNTING MEANS AND SAID PADDLES AT A FIRST GIVEN SPEED TO MAINTAIN THE INGREDIENTS OF SAID ETCHING SOLUTION IN MIXED CONDITION, MEANS FOR ROTATING SAID PADDLE MOUNTING MEANS AND SAID PADDLES AT A SECOND GIVEN SPEED DURING THE ETCHING OPERATION TO SPLASH SAID ETCHING SOLUTION AGAINST A PRINTING PLATE DISPOSED WITHIN SAID TANK AND MEANS INCLUDING TIMER MEANS FOR SELECTIVELY INTERCONNECTING SAID PADDLE MOUNTING MEANS AND ROTATING MEANS FOR NORMALLY ROTATING SAID PADDLES AT SAID FIRST GIVEN SPEED, SAID TIMER MEANS AUTOMATICALLY INTERCONNECTING SAID PADDLE MOUNTING MEANS AND ROTATING MEANS FOR ROTATING SAID PADDLES AT SAID SECOND GIVEN SPEED DURING THE ETCHING OPERATION AS DETERMINED BY SAID TIMER MEANS. 